This invention relates to a method of and apparatus for handling thermoplastic containers that are formed in tandem, that is, open end to open end, after the tandem containers are discharged from a blow molding machine.
Small plastic containers, for example, containers designed for packaging 8 fl. oz. or less of a beverage, are advantageously produced two at a time, in tandem, with the containers joined open end to open end. Typically, the tandem containers of such character are discharged at a fairly high rate from a blow molding machine, for example, a blow molding machine of the wheel type, as described in U.S. Pat. No. 6,171,542 (Struble), with the axes of successive tandem containers desirably extending horizontally and generally parallel to one another, and with opposed ends of the tandems in alignment with one another. However, at the time of the discharge of the tandem containers from the blow molding machine, the axes of such tandem containers are not always precisely parallel to one another and the opposed ends of a tandem are often out of alignment with those of other tandems; further, the tandems are often circumferentially misaligned with one another.
Tandem containers, as heretofore described, must undergo additional processing steps after being discharged from a blow molding machine, and these processing steps include trimming of the xe2x80x9ctailxe2x80x9d from an end of one of the containers, severing the containers of the tandem from one another, and trimming the sealing rims of the containers. All these steps require that the tandems be accurately aligned on an end to end basis. Further, because the tail on one of the containers of the tandem extends on a diametral line that is formed by parting lines between halves of the molds in which the tandems are formed, it is necessary that the tandems be accurately circumferentially positioned prior to the trimming of the tail from an end of each of the tandems.
According to the present invention, there is provided a method of, and an apparatus for, accurately aligning successive tandem thermoplastic containers being discharged from a blow molding machine with their longitudinal central axes extending horizontally, each of the tandem containers being discharged along an axis extending normally to the desired orientation of the longitudinal central axes of the tandem containers. Each of the tandem containers, as described, is made up of a pair of individual containers that are joined open end to open end, and each of the individual containers has an outwardly projecting annular support bead, near its open end, to support the container during filling and capping. The successive tandem containers are conveyed from the blow molding machine in a generally horizontal direction on upwardly facing suction cups on a take-out conveyor, and there is some tendency for individual tandem containers to partly rotate during this step, which can lead to variations in the orientation of diametral tails on an end of the tandem containers, from tandem to tandem.
The tandem containers on the take-out conveyor are transferred to a downwardly inclined chute. The chute has a wedge that is positioned with a narrow end near an inlet end of the chute and a wider end near an outlet end of the chute, and the opposed edges of the wedge are positioned to engage the interiors of the support beads on the containers of the tandem. Thus, as the tandems move down the chute, the edges of the wedge bring tandems into positions where their opposed ends are aligned, even if not properly aligned at the inlet to the inclined chute. Further, such tandem containers are permitted to contact one another in the inclined chute, and this is effective to align their longitudinal central axes parallel to one another, even if not properly aligned at the inlet to the inclined chute.
After exiting the inclined chute, the successive tandems, which are now positioned with their longitudinal central axes extending parallel to each other and with their opposed ends in alignment, are transferred to a spin trimmer along a flat plate by a rotary worm gear mechanism, specifically, a spaced apart pair of parallel and synchronously driven like worm gears, that separates successive tandems by a distance equal to spaces between successive helixes of the worm gear(s). Each such tandem passes over a ridge on the flat plate, and the ridge engages a thin key that extends axially from an end of one of the containers of each of the tandems along a diameter of the tandem, the tail of that container extending from the key and parallel thereto. The ridge engages the key to circumferentially position the tandem so that the tail at its end is properly positioned to be severed from the tandem.
Accordingly, it is an object of the present invention to provide an improved method of, and an apparatus for, handling successive freshly-molded tandem thermoplastic containers to properly position the tandem containers for further processing.
More particularly, it is an object of the present invention to provide a method of, and an apparatus for, the foregoing character to overcome any out of parallel condition of the longitudinal central axes of successive tandem containers, and to correct any out of alignment condition between opposed ends of successive tandem containers.
It is also an object of the present invention to provide a method of, and an apparatus for, the foregoing character to accurately circumferentially orient each successive tandem container so that a linear tail extending diametrically from an end of one of the containers of each of the tandem is properly oriented for removal of the tails from the tandem containers.